Methods and apparatus for dual confinement and ultra-high pressure in an adjustable gap plasma chamber

ABSTRACT

A plasma processing system having a plasma processing chamber configured for processing a substrate is provided. The plasma processing system includes at least an upper electrode and a lower electrode for processing the substrate. The substrate is disposed on the lower electrode during plasma processing, where the upper electrode and the substrate forms a first gap. The plasma processing system also includes an upper electrode peripheral extension (UE-PE). The UE-PE is mechanically coupled to a periphery of the upper electrode, where the UE-PE is configured to be non-coplanar with the upper electrode. The plasma processing system further includes a cover ring. The cover ring is configured to concentrically surround the lower electrode, where the UE-PE and the cover ring forms a second gap.

CROSS REFERENCE TO RELATED APPLICATIONS

This divisional application claims priority to co-pending U.S. patentapplication Ser. No. 12/368,843, filed Feb. 10, 2009, entitled “METHODSAND APPARATUS FOR DUAL CONFINEMENT AND ULTRA-HIGH PRESSURE IN ANADJUSTABLE GAP PLASMA CHAMBER,” which claims priority from U.S.Provisional Application No. 61/139,481, filed on Dec. 19, 2008, all ofwhich are incorporated herein by reference in its entirety for allpurposes.

BACKGROUND OF THE INVENTION

Advances in plasma processing have facilitated growth in thesemiconductor industry. The semiconductor industry is a highlycompetitive market. The ability for a manufacturing company to be ableto process substrates in different processing conditions may give themanufacturing company an edge over competitors. Thus, manufacturingcompanies have dedicated time and resources to identify methods and/orarrangements for improving substrate processing.

A typical processing system that may be employed to perform substrateprocessing may be a capacitively-coupled plasma (CCP) processing system.The plasma processing system may be built to enable processing in arange of process parameters. However, in recent years, the types ofdevices that may be processed have become more sophisticated and mayrequire more precise process control. For example, devices beingprocessed are becoming smaller with finer features and may require moreprecise control of plasma parameters, such as plasma density anduniformity across the substrate, for better yield. Pressure control ofthe wafer area in the etching chamber may be an example of a processparameter affecting plasma density and uniformity.

The manufacturing of semiconductor devices may require multi-stepprocesses employing plasma within a plasma processing chamber. Duringplasma processing of semiconductor device(s), the plasma processingchamber may typically be maintained at a predefined pressure for eachstep of the process. The predefined pressure may be achieved throughemploying mechanical vacuum pump(s), turbo pump(s), confinement ringpositioning and/or combinations thereof, as is well known by thoseskilled in the art.

Conventionally, a valve assembly may be employed to throttle the exhaustturbo pump(s) to attain pressure control for maintaining predefinedpressure conditions in the plasma processing chamber. However, thepressure being controlled by the vat valve may result in a global changein the entire chamber without the capability of providing differentialpressure control in different regions of the chamber.

In the prior art, the pressure in the plasma generating region of theplasma processing chamber (e.g., the region encapsulated by the twoelectrodes and surrounded by the confinement rings) may be controlled byadjusting the gaps between the confinement rings of a confinement ringassembly. Adjusting the gaps controls the flow rate of exhaust gas fromthe plasma generating region and pressure may be affected as a result.The overall gas flow conductance out of the plasma generating region maydepend on several factors, including but not limited to, the number ofconfinement rings and the size of the gaps between the confinementrings. Thus, the operating windows for the pressure range may be limitedby the chamber gap and/or the gaps of these confinement rings.Furthermore, the plasma cross section may be a fixed diameter for theaforementioned process due to the fix diameter of these confinementrings.

In the prior art, a plasma processing chamber configured with thecapability to sustain a plurality of differentiated plasma volumes maybe employed to address the aforementioned problem of plasma of fixedcross section. In an example, a wide-gap configuration may be employedto provide an increased plasma cross section with relatively lowpressure. In another example, a narrow-gap configuration may be employedto provide the conventional plasma cross section but relatively higherpressure may be attained. However, active differentiated pressurecontrol for the system is not provided.

In view of the need to process the substrate in multiple steps, each ofwhich may involve a different pressure, improvement to the capability toprovide differentiated pressure control over a wider range of pressurein plasma processing systems is highly desirable.

SUMMARY OF INVENTION

The invention relates, in an embodiment, to a plasma processing systemhaving a plasma processing chamber configured for processing asubstrate. The plasma processing system includes at least an upperelectrode and a lower electrode for processing the substrate. Thesubstrate is disposed on the lower electrode during plasma processing,where the upper electrode and the substrate forms a first gap. Theplasma processing system also includes an upper electrode peripheralextension (UE-PE). The UE-PE is mechanically coupled to a periphery ofthe upper electrode, where the UE-PE is configured to be non-coplanarwith the upper electrode. The plasma processing system further includesa cover ring. The cover ring is configured to concentrically surroundthe lower electrode, where the UE-PE and the cover ring forms a secondgap.

The above summary relates to only one of the many embodiments of theinvention disclosed herein and is not intended to limit the scope of theinvention, which is set forth is the claims herein. These and otherfeatures of the present invention will be described in more detail belowin the detailed description of the invention and in conjunction with thefollowing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 shows, in accordance with an embodiment of the present invention,a simplified schematic of a plasma processing system configured with anadjustable gap between an upper electrode assembly and a lower electrodeassembly to yield a narrow gap configuration with a symmetric chamberfor ultra-high pressure and/or low conductance regime.

FIG. 2 shows, in accordance with an embodiment of the present invention,a simplified schematic of a plasma processing system configured with anadjustable gap between an upper electrode assembly and a lower electrodeassembly to yield a wide gap configuration with an asymmetric chamberfor low pressure and/or high conductance regime.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will now be described in detail with reference toa few embodiments thereof as illustrated in the accompanying drawings.In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention. Itwill be apparent, however, to one skilled in the art, that the presentinvention may be practiced without some or all of these specificdetails. In other instances, well known process steps and/or structureshave not been described in detail in order to not unnecessarily obscurethe present invention.

In accordance with embodiments of the invention, there are providedmethods and apparatus for providing a wide range of pressure in the sameplasma processing chamber. In some plasma processing systems, thechamber gap (i.e., the gap between the upper and lower electrode) is arecipe parameter and may vary from step to step. In these plasmaprocessing systems, there may be provided a mechanism configured to movethe lower electrode assembly to adjust the chamber gap. In other plasmaprocessing systems, the upper electrode assembly may be moved. In thedisclosure herein, the chamber is assumed to have a moving lowerelectrode. It should be understood, however, that embodiments of theinvention herein apply equally well to chambers in which the upperelectrode is movable (alternatively or additionally).

In one ore more embodiments, the upper electrode is grounded while thelower electrode is powered. In an implementation, the periphery of theupper electrode is provided with an annular, i.e., donut-shaped, ringthat surrounds the upper electrode. The annular extension is referredherein as the upper electrode peripheral extension (UE-PE).

The gap below the UE-PE is to a quartz cover ring may be configured suchthat as the gap between the upper electrode and the lower electrode issufficiently narrowed, there comes a point where the gap below the UE-PEis insufficiently large to sustain plasma below the UE-PE while the gapthat under lies the upper electrode inside of the UE-PE still remainsufficiently large to sustain plasma. In this narrow-gap case, the gapbelow UE-PE may represent an area of very high flow restriction. In anembodiment, the height of the gap below UE-PE may be adjusted to controlthe pressure to attain ultra-high pressure and low conductance in thearea of the gap that under lies the upper electrode inside of the UE-PE.

As the gap between the upper electrode and the lower electrode isgradually enlarged whereas the gap below the UE-PE is insufficientlylarge to sustain plasma while the gap that under lies the upperelectrode inside of the UE-PE still remain sufficiently large to sustainplasma, lower pressure and higher conductance may be achieved for thenarrow-gap configuration in an embodiment.

As the gap between the upper electrode and the lower electrode isfurther gradually enlarged, there comes a point where the gap below theUE-PE is sufficiently large to sustain plasma while the gap that underlies the upper electrode inside of the UE-PE is also sufficiently largeto sustain plasma. In this wide-gap configuration, low pressure and highconductance may be achieved. The confinement rings may be employed tocontain plasma and/or control pressure.

As may be appreciated from the foregoing, the effective RF coupling areaof the powered lower electrode remains the same for both the narrow-gapconfiguration and the wide-gap configuration. However, in the wide-gapconfiguration, the effective RF coupling area of the grounded electrodeis enlarged. Accordingly, the narrow-gap configuration may provide for afirst area ratio of RF coupling while the wide-gap configuration mayprovide for a second area ratio of RF coupling, i.e., larger due to alarger effective RF ground coupling area.

In an embodiment, the difference in gaps (i.e., the gap between theupper electrode and lower electrode at the central region of the upperelectrode and the gap below the UE-PE) may be accomplished by making theUE-PE non co-planar with the upper electrode. For example, the UE-PE mayprotrude below the upper electrode. The UE-PE moves together with theupper electrode in implementation wherein the upper electrode ismovable.

In another embodiment, a lower electrode periphery extension (LE-PE) maybe employed to be non-coplanar with the lower electrode. For example,the LE-PE may be raised above the electrode. In an example, the LE-PEmay be quartz cover ring. The LE-PE moves together with the lowerelectrode in implementation wherein the lower electrode is movable.

The features and advantages of the present invention may be betterunderstood with reference to the figures and discussions (with prior artmechanisms and embodiments of the invention contrasted) that follow.

FIG. 1 shows, in accordance with an embodiment of the present invention,a simplified schematic of a plasma processing system configured with anadjustable gap between an upper electrode assembly and a lower electrodeassembly to yield a narrow gap configuration with a symmetric chamberfor ultra-high pressure and/or low conductance regime. Plasma processingsystem 100 may be a single, double or triple frequency capacitivelydischarged system or may be an inductively coupled plasma system or aplasma system employing a different plasma generating and/or sustainingtechnology. In the example of FIG. 1, radio frequency may include, butare not limited to, 2, 27 and 60 MHz.

Referring to FIG. 1, plasma processing system 100 may be configured withan upper electrode assembly 102 and a lower electrode assembly 104, inan embodiment. The upper electrode assembly 102 and lower electrodeassembly 104 may be separated from each other by a chamber gap 106. Theupper electrode assembly 102 may include at least an upper electrodethat may be grounded or powered by an RF power supply (not shown).

In the example of FIG. 1, upper electrode assembly 102 may be groundedin an embodiment. Further, upper electrode assembly 102 may beconfigured with an inner upper electrode component 102 a and an outerupper electrode component 102 b in an embodiment. Outer electrodecomponent 102 b may be an annular extension of inner upper electrode 102a in an embodiment. Herein, outer electrode component 102 b may bereferred to as an upper electrode peripheral extension (UE-PE).

As shown in FIG. 1, inner upper electrode component 102 a and UE-PE 102b may be formed from different components as shown in FIG. 1.Alternatively, inner upper electrode 102 a and UE-PE 102 b may be formedas a monolithic unit in an embodiment as shown in FIG. 2. Further, innerupper electrode 102 a and/or UE-PE 102 b may be formed from a pluralityof components in an embodiment.

Lower electrode assembly 104 may be configured with an electrostaticchuck (ESC) 110, an edge ring 112, an insulator ring 114, a focus ring116, a quartz cover ring 118, confinement ring assembly 124, and/or aby-pass ring 120 in an embodiment. As shown in FIG. 1, by-pass ring 120may be formed from aluminum. In an embodiment, by-pass ring 120 may beconfigured with a by-pass cavity 122 to allow gas to exhaust throughby-pass cavity 122. As shown in FIG. 1, a vat valve 134 coupled to aturbo molecular pump (TMP) 136 may be employed to exhaust processed gasfrom plasma processing system 100. The features of the aforementionedcomponents are well known by those skilled in the art and will not bediscussed in detail to simplify the discussion.

In an embodiment, UE-PE 102 b may be configured with a step, i.e., chokepoint 126. As a result of the step, the lower surface of UE-PE 102 b mayextend or protrude below the lower surface of inner upper electrode 102a. As shown in FIG. 1, the lower surface of UE-PE 102 b and the topsurface of quartz cover ring 118 may be separated by a second gap 128 inan embodiment. The size of gap 128 may be adjustable by moving upperelectrode assembly 102 and/or lower electrode assembly in an embodiment.

In an embodiment, the choke point may be formed by making a nonco-planar step. For example, the UE-PE may extend or protrude below thesurface of the upper electrode. Alternatively or additionally, a lowerelectrode periphery extension (LE-PE) may be employed to be non-coplanarwith the lower electrode. For example, the LE-PE may be raised above theelectrode. In an example, the LE-PE may be quartz cover ring 118.

As shown in FIG. 1, plasma processing system 100 may be configured withtwo possible plasma sustaining regions: region 130 a OR regions 130 aplus 128 plus 130 b. In an embodiment, region 130 a may be capable ofsustaining plasma whenever chamber gap 106 is sufficiently large tosustain plasma. Whereas, regions 130 a plus 128 plus 130 b may becapable of sustaining plasma whenever gap 128 in the choke region issufficiently large to sustain plasma in an embodiment. This is depictedin FIG. 2.

During plasma processing, processed gas (not shown) may be supplied intochamber gap 106. The processed gas being supplied into chamber gap 106may be excited into a plasma state by RF power supplied to lowerelectrode assembly 104. Consider the situation wherein, for example,lower electrode assembly 104 may be moved to create a narrow-gapconfiguration wherein the size of gap 128 may be insufficient large(relative to the mean free path) to sustain plasma.

In the narrow-gap configuration of FIG. 1, plasma may be sustained inregion 130 a of chamber gap 106 in an embodiment. Gap 128 of chokeregion may be insufficiently large to sustain plasma. Therefore, region130 b may be incapable of sustaining plasma. In the narrow gapconfiguration confinement ring assembly 124 is pulled up to limitadditional flow obstructions.

In an embodiment, the upper electrode and lower electrode may be sizedsuch that in the narrow-gap configuration, a 1:1 area ratio may beachieved, making the chamber a symmetric chamber in the narrow-gapconfiguration.

In the narrow-gap configuration, differential pressure between region130 a and the rest of plasma processing system may be attained andcontrolled in an embodiment. In an example, the pressure in chamber gap106 may be controlled by an active feedback loop. In an embodiment, thepressure in region 130 a may be measured and gap 128, vat valve 134and/or gas flow rate may be adjusted to control the pressure in region130 a.

Consider the situation wherein, for example, ultra-high pressure, e.g.,in the Torr range, may be desired in region 130 a during plasmaprocessing of a substrate 108. Lower electrode assembly 104 may be movedto a reduced height to form a very narrow gap for gap 128. The chokeregion of gap 128 may represent an area of very high flow restrictionchoking the gas flow significantly. In an embodiment, the height of gap128 is insufficiently large to sustain plasma in gap 128 and/or region130 b.

Through the aforementioned active pressure feedback loop, pressure inregion 130 a may be controlled by adjusting the height of gap 128. Forexample, the pressure in region 130 a may be increased by furtherreducing the height of gap 128. In an embodiment, gap 128 remainsinsufficiently large to sustain plasma in region 130 b throughout therange of pressure controlled through adjusting gap 128.

Alternatively and/or additionally, the pressure in region 130 a may becontrolled by adjusting the flow of processed gas through region 130 ain an embodiment. In an example, the flow of processed gas may beincreased to increase pressure in region 130 a to increase pressure toattain ultra-high pressure in region 130 a.

Alternatively and/or additionally, pressure control of region 130 a maybe achieved by adjusting vat valve 134 upstream of TMP 136 in anembodiment. In an example, vat valve 134 may be throttle closed to backpressure plasma chamber region to increase pressure to attain ultra-highpressure in region 130 a.

Referring to FIG. 1, a confinement ring set 124 may not be employed inpressure control for ultra-high pressure regime because flow restrictionis insignificant in comparison to the flow restriction from gap 128. Inaddition, confinement ring set 124 is parallel of by-pass ring 120,which has even higher conductance than the gaps between confinement ringset 124. For example, confinement ring set 124 may be configured in thecollapsed state resting on shoulder 132 of by-pass ring 120 or may bepulled up into the wafer transport position as shown in FIG. 1. Gasconductance through by-pass cavity 122 of by-pass ring 120 may renderpressure control from confinement ring set 124 inconsequential.

Accordingly, region 130 a may be able to attain ultra-high pressure,e.g., up to about 5 Torr, due to the high flow rate and/or the high flowrestriction. Thus, a symmetric chamber with a narrow gap configurationmay attain ultra-high pressure and/or low conductance independent of therest of the processing chamber in an embodiment.

In the prior art, gap 128 may be employed to extinguish plasma in region130 b by narrowing the size of gap 128 to be insufficient large tosustain plasma. In contrast, gap 128 may be employed not only toextinguish plasma in region 130 b, but gap 128 may be adjusted tocontrol pressure in region 130 b. Thus, gap 128 may be narrowed beyondthe point to extinguish plasma for pressure control.

Consider another situation wherein, for example, low pressure and/orhigh conductance may be desired in region 130 a during plasma processingfor the configuration with a symmetric chamber and narrow gap. FIG. 1 isemployed to illustrate the example of low pressure and/or highconductance regime with the symmetric chamber. For example, lowerelectrode assembly 104 may be moved such that gap 128 is sufficientlylarge to reduce flow restriction but still able to prevent plasmaignition in region 130 b in an embodiment.

Referring to FIG. 1, plasma is sustained in region 130 a. Gap 128 issufficiently narrowed to extinguish plasma, and plasma is not sustainedin region 130 b. In an embodiment, gap 128 may be sufficiently large toincrease gas conductance resulting in lower pressure in region 130 a. Inan embodiment, pressure control of region 130 a may be attained byadjusting gap 128. The upper range for the size of gap 128 may belimited to the size of gap 128 (relative to the mean free path) tosustain plasma in an embodiment.

Alternatively and/or additionally, the pressure in region 130 a may becontrolled by adjusting the flow of processed gas through region 130 ain an embodiment. In an example, the flow of processed gas may bereduced to decrease pressure in region 130 a.

Alternatively and/or additionally, pressure control of region 130 a maybe achieved by adjusting vat valve 134 upstream of TMP 136 in anembodiment. In an example, vat valve 134 may be throttle opened toreduce pressure in region 130 a.

In the low pressure regime with the symmetric chamber, confinement ringset 124 may be employed to control pressure. Referring to FIG. 1,confinement ring set 124 may be lowered and pressure in region 130 a maybe controlled by adjusting the gaps between confinement ring set 124.Methods for controlling pressure employing confinement ring set is wellknown by those skilled in the art and is not discussed in detail tosimplify discussion.

Accordingly, a lower pressure regime may be achieved with symmetricchamber configuration by adjusting gap 128 to increase conductance whilepreventing external region 130 b from sustaining plasma. Pressure inregion 130 a may be controlled by adjusting gap 128, confinement ringset 124, gas flow rate, and/or vat valve 134.

FIG. 2 shows, in accordance with an embodiment of the present invention,a simplified schematic of a plasma processing system configured with anadjustable gap between an upper electrode assembly 102 and a lowerelectrode assembly 104 to yield a wide gap configuration with anasymmetric chamber for low pressure and/or high conductance regime. FIG.2 is discussed in relation to FIG. 1 to facilitate understanding.

Consider the situation wherein, for example, low pressure, e.g., as lowas about 5 mili-Torr, may be desired for processing of substrate 108 inplasma processing system 200, as shown in FIG. 2. The low pressureand/or high conductance may be attained by moving lower electrodeassembly 104 in the direction of an arrow 240 to increase the height ofgap 128 in an embodiment. The increase in height of gap 128 may resultin higher conductance. In an embodiment, gap 128 is sufficiently largeand plasma may be sustained in a region 230. Region 230 may extend fromthe center of the chamber out to the inner edge of confinement ring set124. As shown in FIG. 2, confinement ring set 124 may be employed toconfine plasma within a specific region.

In the wide-gap configuration of FIG. 2, the area ratio of the groundedupper electrode to the powered lower electrode may be high, i.e., theratio may be greater than 1:1, making the chamber asymmetric. Incontrast to the symmetric configuration, plasma is sustained in region230 for the asymmetric configuration as shown in FIG. 2 instead ofplasma being only sustained in region 130 a as shown in FIG. 1. Forexample, a high ratio of ground to powered RF electrode areas may resultin high bias voltage and high ion energy at substrate 108 for thewide-gap configuration.

As shown in FIG. 2, gas may flow out of region 230 through by-passcavity 122 of by-pass ring 120 contributing to the capability ofattaining low pressure for the asymmetric configuration. Due to by-passcavity 122 and the increased height of gap 128, the high pressure thatmay be attained in the asymmetric configuration may be limited.

In the low pressure asymmetric configuration, pressure in region 230 maybe controlled by adjusting the gaps of confinement ring set 124, asshown in FIG. 2. Confinement ring set 124 may be lowered and pressuremay be controlled by adjusting the gaps between confinement ring set124.

Alternatively and/or additionally, the pressure in region 230 may becontrolled by adjusting the flow of processed gas through region 130 inan embodiment. In an example, the flow of processed gas may be reducedto decrease pressure in region 230.

Alternatively and/or additionally, pressure control of region 230 may beachieved by adjusting vat valve 134 upstream of TMP 136 in anembodiment. In an example, vat valve 134 may be throttle opened toreduce pressure in region 230.

Accordingly, a lower pressure regime with increased conductance may beachieved in a wide-gap configuration of gap 128 with an asymmetricchamber. Pressure in region 230 may be controlled by adjusting gapsbetween the confinement ring set 124, gas flow rate, and/or vat valve134.

As can be appreciated from the foregoing, embodiments of the inventionpermit differentiated pressure control to provide a wide range ofpressure and/or conductance in a plasma processing system. The range ofpressure that may be attained may be from about 5 mili-Torr to about 5Torr. In the ultra-high pressure range, plasma processing in the gammamode may be possible. Furthermore, the different gap configurations mayallow for control of grounded upper electrode to powered lower electrodearea ratio allowing control of wafer bias and ion energy as well as ionenergy distribution. Thus, substrate requiring various recipes over awide range of pressure and/or bias and ion energy or ion energydistribution may be performed using the same plasma processing chamberreducing cost and/or time delay that may incur in employing multipleplasma processing chambers.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents, which fall withinthe scope of this invention. It should also be noted that there are manyalternative ways of implementing the methods and apparatuses of thepresent invention. Furthermore, embodiments of the present invention mayfind utility in other applications. The abstract section is providedherein for convenience and, due to word count limitation, is accordinglywritten for reading convenience and should not be employed to limit thescope of the invention. It is therefore intended that the invention beinterpreted as including all such alterations, permutations, andequivalents as fall within the true spirit and scope of the presentinvention.

What is claimed is:
 1. A method for controlling pressure in a plasmaprocessing chamber, said method comprising: providing at least an upperelectrode and a lower electrode for processing a substrate, saidsubstrate being disposed on said lower electrode during plasmaprocessing, where said upper electrode and said substrate forms a firstgap, wherein said upper electrode is grounded and wherein said lowerelectrode is powered; providing an upper electrode peripheral extension(UE-PE), said UE-PE is mechanically coupled to a periphery of said upperelectrode, where said UE-PE is also grounded and configured to benon-coplanar with said upper electrode; providing a cover ring formed ofquartz that surrounds said lower electrode, where a lower surface ofsaid UE-PE and an upper surface of said cover ring forms a second gap,wherein said second gap is smaller than said first gap and wherein oneof said upper electrode, along with said UE-PE, and said lowerelectrode, along with said cover ring, is movable in a directionperpendicular to a planar surface of said lower electrode to form atleast a first operating mode and a second operating mode whereby saidsecond gap in said second operating mode is larger than said second gapin said first operating mode, said first operating mode characterized byhaving plasma in said first gap but not in said second gap and by afirst RF coupling area ratio of grounded electrode area to poweredelectrode area, said second operating mode characterized by havingplasma in said first gap and also plasma in said second gap and by asecond RF coupling area ratio of grounded electrode area to poweredelectrode area that is larger than said first RF coupling area ratio;generating a plasma within said plasma processing chamber to processsaid substrate; and adjusting said second gap and said first gap tocontrol pressure within said plasma processing chamber.
 2. The method ofclaim 1, wherein said UE-PE and said upper electrode is formed as amonolithic unit.
 3. The method of claim 1, wherein said UE-PE and saidupper electrode is formed from a plurality of components.
 4. The methodof claim 1, wherein said plasma processing chamber further includes aset confinement ring, said method including: deploying said set ofconfinement rings to regulate a process pressure when said first gapexists between said upper electrode and said lower electrode; andcompletely stowing said set of confinement rings when said second gapexists between said upper electrode and said lower electrode due to saidadjusting.
 5. The method of claim 1, wherein said adjusting is in-situ.6. The method of claim 1, wherein said adjusting includes moving one ofsaid upper electrode and said lower electrode in a directionperpendicular to a planar surface of said lower electrode.
 7. The methodof claim 6, wherein only said upper electrode of said upper electrodeand said lower electrode is adjustable.
 8. The method of claim 6,wherein only said lower electrode of said upper electrode and said lowerelectrode is adjustable.
 9. The method of claim 6, wherein saidadjusting results in at least a first area ratio and a second arearatio, said first area ratio representing 1:1 and thereby emulating asymmetric plasma processing chamber, said second area ratio is otherthan 1:1 and thereby emulating a non-symmetric plasma processingchamber.
 10. The method of claim 1, further comprising: providing aby-pass ring having a by-pass cavity; and evacuating at least a portionof exhaust gas produced by said processing.
 11. A method for controllingpressure in a capacitively coupled plasma processing chamber, saidmethod comprising: providing a grounded upper electrode; providing apowered lower electrode for supporting a substrate during a processing,said lower electrode being movable in a direction perpendicular to aplanar surface of said substrate when said substrate is disposed on saidlower electrode, whereby said upper electrode and said substrate forms afirst gap; providing a cover ring formed of quartz that surrounds saidlower electrode, said cover ring moving together with said lowerelectrode; and providing a grounded upper electrode peripheral extension(UE-PE) configured to concentrically surround said upper electrode andis fixed relative to said upper electrode, whereby at least a portion ofa lower surface of said UE-PE is configured to be non-coplanar with alower surface of said upper electrode, whereby said at least a portionof said lower surface of said UE-PE and an upper surface of said coverring forms a second gap and whereby said second gap is narrower thansaid first gap irrespective of a position of said movable lowerelectrode, wherein said lower electrode is movable to create at least afirst plasma mode and a second plasma mode, said first plasma modehaving both said first gap and said second gap capable of sustaining aplasma therein and is characterized by a first RF coupling area ratio ofgrounded electrode area to powered electrode area, said second plasmamode having said first gap having a height capable of sustaining saidplasma in said first gap and said second gap having a height too narrowto sustain said plasma in said second gap and is characterized by asecond RF coupling area ratio of grounded electrode area to poweredelectrode area that is smaller than said first RF coupling area ratio;generating a plasma within said capacitively coupled plasma processingchamber to process said substrate; and adjusting said second gap andsaid first gap to control pressure within said capacitively coupledplasma processing chamber.
 12. The method of claim 11, wherein saidlower electrode position is variable while in said first plasma mode,thereby sustaining said plasma in said first gap and said second gap fora plurality of lower electrode positions.
 13. A method for controllingpressure in a capacitively coupled plasma processing chamber, saidmethod comprising: providing at least an upper electrode and a lowerelectrode for processing said substrate, said substrate being disposedon said lower electrode during plasma processing, where said upperelectrode and said substrate forms a first gap, wherein said upperelectrode is grounded and wherein said lower electrode is powered;providing an upper electrode peripheral extension (UE-PE), said UE-PE ismechanically coupled to a periphery of said upper electrode, where saidUE-PE is also grounded; and providing a cover ring formed of quartz thatsurrounds said lower electrode, wherein an upper surface of said coverring is non-coplanar relative to an upper surface of said lowerelectrode, a lower surface of said UE-PE and an upper surface of saidcover ring forms a second gap, wherein said second gap is smaller thansaid first gap and wherein one of said upper electrode, along with saidUE-PE, and said lower electrode, along with said cover ring, is movablein a direction perpendicular to a planar surface of said lower electrodeto form at least a first operating mode and a second operating modewhereby said second gap in said second operating mode is larger thansaid second gap in said first operating mode, said first operating modecharacterized by having plasma in said first gap but not in said secondgap and by a first RF coupling area ratio of grounded electrode area topowered electrode area, said second operating mode characterized byhaving plasma in said first gap and also plasma in said second gap andby a second RF coupling area ratio of grounded electrode area to poweredelectrode area that is larger than said first RF coupling area ratio;generating a plasma within said capacitively coupled plasma processingchamber to process said substrate; and adjusting said second gap andsaid first gap to control pressure within said capacitively coupledplasma processing chamber.
 14. The method of claim 13, wherein the lowersurface of UE-PE slopes down at an angle from a point coplanar with theupper electrode to a point that is beneath a lower surface of the upperelectrode.
 15. The method of claim 13, wherein said first operating modeprovides a narrow gap configuration with a symmetric chambercharacterized by at least one of an ultra-high pressure or a lowconductance regime.
 16. The method of claim 13, wherein said secondoperating mode provides a wide gap configuration with an asymmetricchamber characterized by at least one of a low pressure or a highconductance regime.